JP4862316B2 - Laminated metal plate - Google Patents

Description

The present invention relates to laminated metal sheet using a thermoplastic polyester resin film arm laminate for a container for laminated metal sheet used for food cans can body and the lid or the like.

  Traditionally, tin-free steel (TFS), which is a metal material used for containers such as food cans, and metal plates such as aluminum have been painted, but the technique of applying this coating involves a complicated baking process. In addition, it has a problem of requiring a large amount of processing time and discharging a large amount of solvent. Therefore, recently, a laminated metal plate obtained by laminating a thermoplastic polyester resin film on a heated metal plate has been used.

  The polyester resin film used for such applications is required to have the following performance. That is, it has excellent adhesion to the metal plate, there is no deformation such as elongation or compression due to processing at the time of can making, there is no deterioration due to friction at the time of can making or lowering of adhesion, drying after can making, printing It does not crystallize or deteriorate due to heating such as baking, retort sterilization, etc., and does not cause peeling, shrinkage, cracks, pinholes, etc. There may be no corrosion or peeling when in contact with the contents, or no cloudiness. Furthermore, it is also required that the scent component of the contents of the can be adsorbed on the resin film, and that the flavor of the contents is not impaired by the elution or smell of the resin film (hereinafter referred to as flavor property).

  For example, Patent Document 1 discloses a metal plate coated with a polyethylene terephthalate resin from the viewpoint of processability, heat resistance, corrosion resistance, flavor properties, etc., and Patent Document 2 covers a polybutylene terephthalate resin. Proposed metal plates have been proposed. Furthermore, the coating resin used for such a metal can material is required to have excellent workability that can follow the drawing and ironing process, and has excellent adhesion that does not peel off from the metal plate, Since excellent impact resistance that can withstand impact during canned manufacturing and transportation is also required, Patent Document 3 and Patent Document 4 include polyethylene terephthalate resin films that originally have food hygiene and flavor properties. A method for producing a resin film having excellent processability, adhesion, and impact resistance has been proposed by controlling the crystal orientation with a laminating technique or the like. The resin film disclosed in such a technique satisfies the current required level of workability, adhesion and impact resistance.

  However, in this field, the thickness of the material has been decreasing year by year due to weight reduction, and the metal plate laminating resin is subject to more severe processing. It is difficult to achieve both compatibility and impact resistance. This is because workability and impact resistance largely depend on the degree of crystal orientation (plane orientation) of the resin layer, but these dependencies tend to contradict each other. That is, when the number of oriented crystals in the resin layer increases, plastic deformation is hindered at the crystal portion, and the workability decreases. For this reason, from the viewpoint of workability, the smaller the number of oriented crystals, the better. However, since this crystal portion serves as a site that stops the progress of cracking due to impact, the more oriented crystals are better from the viewpoint of impact resistance. Therefore, at present, the amount of oriented crystals is adjusted so as to allow workability and impact resistance, but in order to cope with more severe processing in the future, adjustment of such crystal amount alone will reach the limit. Therefore, development of a new highly workable film and a laminated metal plate covering the same is expected.

  In response to such needs, a technique has been studied in which a polyolefin resin is mixed with a polyester resin to achieve both high workability and excellent impact resistance. For example, Patent Documents 5 and 6 disclose a technique for laminating a resin film made of a saturated polyester resin and an ionomer resin on a metal plate. Although it has been shown that this resin film can maintain impact resistance even in an amorphous state, in reality, sufficient impact resistance cannot be obtained only by adding an ionomer resin. Since it is hindered by the addition of the ionomer resin, the inherent mechanical strength of the polyester resin is lowered, and the resin film is broken at the time of processing, or the adhesion to the base metal is deteriorated after processing or after heating.

  Patent Document 7 and Patent Document 8 show that impact resistance can be improved by laminating a resin film made of polyester resin, polyester elastomer, and ionomer resin on a metal plate. However, the effect of improving the impact resistance of the resin film is negligible due to its low ability to relieve the impact force of the polyester elastomer. In addition, as with the case where no elastomer is added, the base metal after processing or heating is not affected. Inferior in adhesion.

  In order to solve the above problems, the present inventors have proposed a laminated metal plate in Patent Document 9 that is coated with a resin film in which a specific amount of a granular modified polyolefin resin is dispersed in a polyester resin. This resin film has remarkably high workability, excellent impact resistance and flavor, and is excellent in adhesion to a base metal after processing and after heating. Moreover, in this resin film, since the resin structure can be stably obtained regardless of the processing conditions, it has been confirmed that such high performance can be stably obtained, and characteristics such as corrosion resistance are sufficient.

  Such excellent characteristics can be obtained when a granular modified polyolefin resin containing a specific amount of a functional group derived from carboxylic acid is dispersed in a polyester resin. This is because the modified polyolefin resin is most stably dispersed in the polyester resin, and the modified polyolefin resin itself has excellent mechanical properties.

  In particular, the reason why workability and impact resistance are compatible in this resin film is presumed as follows. That is, when destructive force is applied to the resin due to severe processing or impact, cracks occur in the polyester resin and it grows and breaks, but a granular modified polyolefin resin with an appropriate composition and size is contained in the polyester resin. If it is dispersed in the cracks, the progress of cracks is suppressed by the stress relaxation by the modified polyolefin resin, and the breakage can be suppressed. Furthermore, the plastic deformation of the polyester resin is promoted at the periphery where such a modified polyolefin resin and the polyester resin are in contact with each other, and the effect of relaxing the stress concentration leading to the destruction and making the resin difficult to break is also expected.

However, when such a laminated metal plate is used in a container such as a food can, there remains a problem that when the contents are taken out from the container, the contents are firmly attached to the inner surface of the container and the contents are difficult to take out. Although this problem is extremely important for ensuring consumers' willingness to purchase, the conventional laminated metal sheet for containers has not been studied at all for improving the ease of taking out the contents. . Therefore, as a result of intensive studies to ensure the content take-out property, the present inventors added a specific wax (carnauba wax) in the polyester resin as disclosed in Patent Document 10, and the resin surface In this way, it was possible to improve the extractability of fat-rich contents (contents with poor adhesion: a mixture of meat, eggs, carbohydrates, etc.).
JP 59-232852 Japanese Unexamined Patent Publication No. 1-180336 Japanese Patent Laid-Open No. 5-269920 JP-A-6-320669 JP-A-7-195617 Japanese Unexamined Patent Publication No. 7-195618 Japanese Unexamined Patent Publication No. 7-290643 JP-A-7-290644 JP 2003-226762 A JP 2001-328204

  However, the technique described in Patent Document 10 has not been able to obtain good extractability for contents having a high content of proteins and lipids such as tuna and corned beef with strong adhesion. This is presumably because the protein has many polar groups, so that hydrogen bonds are easily generated with the resin, and the adhesion of lipids is increased from the protein adhering to the resin surface.

The present invention has been made to solve such problems. In addition to the above-described processability, impact resistance, corrosion resistance, adhesion, flavor properties, etc., the present invention has a high protein, low lipid content removability. and to provide a laminated metal sheet using a thermoplastic polyester resin film arm for good metal plate laminate.

  The present inventors have developed a resin film in which a granular modified polyolefin resin excellent in processability, impact resistance, corrosion resistance, adhesion, and flavor properties is dispersed in a polyester resin, while maintaining those characteristics, As a result of investigating improving the take-out property of protein and high lipid content, when used as a container, control the interface free energy for water on the surface of the resin film in contact with the content to be 20 mN / m or less. Was found to be effective.

The present invention has been made on the basis of such knowledge, and a granular carboxylic acid having a particle diameter of 0.1 to 5 μm in which a functional group derived from carboxylic acid is contained in an amount of 2 to 20% by mass in terms of a mass ratio in terms of carboxylic acid. modified polyolefin resin is contained 3-30 wt% in mass ratio, and the resin layer surface free energy is less than 20 mN / m for water of the surface (resin layer a) possess at least one side surface, the resin layer a A thermoplastic polyester resin film for laminating a metal plate, the surface of which is coated with a hydrophilic polymer, is coated on at least one surface of the metal plate so that the resin layer A is the surface. Provide a laminated metal sheet . The resin other than the resin layer A in the film may be the same resin as the resin layer A, or may be a thermoplastic polyester resin different from the resin of the resin layer A.

  The thickness of the film is preferably 5 to 50 μm. The thickness of the resin layer A is also preferably 5 to 50 μm.

The present invention, excellent processability and having impact resistance, and laminated metal sheet using a suitable metal plate the thermoplastic polyester resin film arm laminate in a container the content of proteins and lipids are packed with high contents Can be manufactured. The laminated metal plate of the present invention is suitable for containers for drawing and the like, particularly for food can containers.

  The thermoplastic polyester resin film for laminating metal plates of the present invention is a granular carboxylic acid modified with a particle size of 0.1 to 5 μm containing functional groups derived from carboxylic acid in an amount of 2 to 20% by mass in terms of carboxylic acid. The resin film has a polyester resin layer A containing 3 to 30% by mass of a polyolefin resin and having an interface free energy with respect to water of 20 mN / m or less on at least one surface. As described above, the resin of the film other than the resin layer A is the same resin as the resin layer A or a thermoplastic polyester resin different from the resin of the resin layer A.

  As the components of the thermoplastic polyester resin of the present invention, those obtained by arbitrarily copolymerizing various aromatic dicarboxylic acids and aliphatic dicarboxylic acids as acid components and various aliphatic diols and aromatic diols as glycol components are used. .

  Specific examples of the acid component include terephthalic acid, phthalic acid, isophthalic acid, 1,4-naphthalenedicarboxylic acid, 2,3-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, and 2,7-naphthalenedicarboxylic acid. 4,4'-biphenyldicarboxylic acid, diphenic acid, diphenyl ether carboxylic acid, 5-sulfoisophthalic acid, diphenoxyethanedicarboxylic acid, adipic acid, oxalic acid, malonic acid, succinic acid, malic acid, citric acid, glutaric acid, Dimer acid, pimelic acid, speric acid, azelaic acid, sepacic acid, dodecadioic acid, trans-1,4-cyclohexanedicarboxylic acid and the like are used. In particular, terephthalic acid and / or isophthalic acid as the main component is preferable from the viewpoint of balance between mechanical properties and flavor properties.

  Specific examples of the glycol component include ethylene glycol, propylene glycol, 1,4-butanediol, 1,3-butanediol, 1,2-butanediol, neopentyl glycol, pentamethylene glycol, hexamethylene glycol, and diethylene glycol. , Triethylene glycol, tetraethylene glycol, polyethylene glycol, trans-1,4-cyclohexanedimethanol, cis-1,4-cyclohexanedimethanol, bisphenols, p-xylene glycol, hydroquinone, 2,2-bis (4- β-hydroxyethoxyphenyl) propane, hydrogenated bisphenol A and the like are used. In particular, those based on ethylene glycol and / or 1,4-butanediol are preferred from the viewpoint of balance between mechanical properties and flavor properties.

  That is, terephthalic acid and ethylene glycol are the main components, and / or terephthalic acid and isophthalic acid and ethylene glycol are the main components, and / or terephthalic acid and ethylene glycol and 1,4-butanediol, and / or terephthalic An acid, ethylene glycol and 1,4-cyclohexanedimethanol as main components are particularly suitable from the viewpoint of the balance between mechanical properties and flavor properties in a mixed resin state.

  As the thermoplastic polyester resin, a polyester resin having polyethylene terephthalate and / or isophthalic acid copolymerized polyethylene terephthalate as a main basic skeleton is preferable. Polyester resin having polyethylene terephthalate and / or isophthalic acid copolymerized polyethylene terephthalate as the main basic skeleton is a part of the polyester resin skeleton containing only ethylene glycol and terephthalic acid as a structural unit and / or ethylene glycol, terephthalic acid and isophthalic acid. The total of the parts having a structural unit occupies 90% by mass or more, and the acid component may be optionally copolymerized with various aromatic dicarboxylic acids and aliphatic dicarboxylic acids at other sites.

  The polyester resin used in the present invention preferably has a glass transition temperature (Tg) of 50 to 120 ° C. More preferably, it is 60-100 degreeC. When the glass transition temperature is less than 50 ° C, the heat resistance of the polyester resin is inferior, so that scratches are easily generated due to the temperature rise during processing. May be inferior. The low temperature crystallization temperature (Tc) is usually 130 to 210 ° C, preferably 140 to 200 ° C, and the melting point (Tm) is usually 210 to 265 ° C, preferably 220 to 260 ° C. If the low-temperature crystallization temperature is less than 130 ° C, crystallization is likely to occur, so crystallization occurs in the retort sterilization treatment (high temperature and high humidity treatment of about 120 ° C, hereinafter referred to as "retort treatment"). Cracks and peeling easily occur. On the other hand, those having a low temperature crystallization temperature exceeding 210 ° C. may be inferior in mechanical strength such as processability and impact resistance of the polyester resin. When the melting point is less than 210 ° C., the resin deteriorates due to heat during processing, and cracks and pinholes are likely to occur. On the other hand, when the melting point exceeds 265 ° C., crystallization proceeds by heat treatment such as drying during processing and printing baking, and cracks and pinholes are likely to occur. The glass transition temperature, low-temperature crystallization temperature, and crystal melting temperature were measured using a differential scanning calorimeter (DSC) with a sample amount of 10 mg and a temperature increase rate of 10 ° C / min. It is the value.

  In the present invention, in the dicarboxylic acid component constituting the polyester resin, the molar ratio of the total terephthalic acid amount and the total isophthalic acid amount is preferably 97: 3 to 85:15. In the mixed resin in the present invention, the modified polyolefin in the resin prevents the crystallization of the polyester resin, and the adhesion and corrosion resistance due to processing and heating are less likely to occur. This ratio spreads to the terephthalic acid rich side, and it is possible to use a homoethylene terephthalate resin containing no isophthalic acid as the polyester resin. Furthermore, if the isophthalic acid ratio is 3 mol%, the adhesion after processing and heating is drastically improved. When the ratio of the total terephthalic acid amount to the total isophthalic acid amount is more than 85:15, the melting point is lowered and the heat resistance during processing may be inferior. In particular, for retort processing, the main monomer component constituting the thermoplastic polyester resin, dicarboxylic acid is terephthalic acid, diol component is ethylene glycol and 1,4-butanediol, the ratio of both (diol In the component, the ratio of ethylene glycol amount and 1,4-butanediol amount) in a molar ratio of 20:80 to 80:20 is suitable. A range of 60:40 to 30:70 is most suitable. In the polyester resin containing the polyolefin resin as described above, the modified polyolefin resin in the resin hinders the crystallization of the polyester resin. Therefore, particularly in the retort treatment, the strength of the polyester resin is insufficient and the cohesive failure is likely to occur. was there. In response to such a problem, by mixing polybutylene terephthalate, which has a particularly high crystallization rate, with polyethylene terephthalate in a predetermined ratio, crystallization of the polyester resin is accelerated, and cohesive failure is less likely to occur even in retort processing. Such an effect is particularly remarkable in the prevention of a phenomenon in which water vapor that has entered the resin film during retort treatment causes the resin film to cohesively break and cause white turbidity in a lid material laminated with a resin film. Such problems can be solved by use. If the ratio of polyethylene terephthalate to polybutylene terephthalate is more than 80:20 in terms of molar ratio, the crystallization rate will not be sufficiently high and the above effect cannot be expected. On the other hand, when the amount of polybutylene terephthalate is larger than 20:80, the melting point is low and the heat resistance is poor.

  A modified polyolefin resin having a functional group derived from a carboxylic acid mixed in a polyester resin improves impact resistance and does not adversely affect other properties such as processability and heat resistance. It is necessary that the particle diameter be 0.1 to 5 μm in an equivalent sphere equivalent meter. Here, it is preferable that at least 30% by mass of the total modified polyolefin resin has a particle diameter of 0.1 to 5 μm in terms of equivalent sphere diameter. When the modified polyolefin resin is dispersed in the polyester resin, a wide particle distribution occurs from very fine particles with a particle size of 0.1 μm or less to large particles with a particle size exceeding 5 μm. However, particles with a particle size of less than 0.1 μm The particles having a particle diameter exceeding 5 μm do not improve or rather deteriorate the physical properties such as processability of the mixed resin. From the viewpoint of suppressing deterioration of physical properties, the mass ratio of particles having a particle diameter exceeding 5 μm is preferably 1% or less. Here, the particle diameter of the modified polyolefin resin dispersed in the resin film is determined by measuring the major axis and the minor axis one by one by etching the surface polyester resin with an alkaline aqueous solution to leave the modified polyolefin particles. (Equivalent sphere equivalent) was calculated, and the volume ratio, the number of particles in the film per side of 10 μm, was determined.

  The mass ratio of the modified polyolefin resin in the total resin needs to be in the range of 3 to 30% by mass. When the mass ratio of the modified polyolefin resin is less than 3% by mass, the impact resistance is not sufficiently improved, and when it exceeds 30% by mass, the workability and heat resistance are deteriorated.

The glass transition temperature of the modified polyolefin resin is preferably 0 ° C. or lower. More preferably, it is −30 ° C. or lower. When the glass transition temperature exceeds 0 ° C, the impact resistance, particularly the low temperature impact resistance, is poor. Further, it is desirable that the modified polyolefin resin has a Young's modulus at room temperature of 250 MPa or less and a breaking elongation of 200% or more. More desirably, the Young's modulus is 100 MPa or less and the elongation at break is 500% or more. The molecular weight of the modified polyolefin resin is not particularly limited, but the number average molecular weight is preferably 2 × 10 ³ or more and 1 × 10 ⁶ or less. If it is less than 2 × 10 ³ or exceeds 1 × 10 ⁶ , the mechanical properties may be inferior, impact resistance may be reduced, and processing may be difficult.

  The functional group derived from carboxylic acid needs to be contained in a mass ratio in terms of carboxylic acid of 2 to 20% by mass, more preferably 3 to 12% by mass. In this content range, the affinity with the polyester resin and the dispersibility in the polyester resin are maximized. The stronger the modified polyolefin resin has a higher affinity with the polyester resin, the higher the mitigating effect against breakage between different resins at the time of impact, and the higher the impact resistance. In addition, aggregation of the modified polyester grains during processing is suppressed, and variation in performance due to processing conditions is reduced. Such an effect is obtained when the weight ratio of the functional group in terms of carboxylic acid is 2% by mass or more, and when it exceeds 20% by mass, the affinity with the polyester resin is decreased and the impact resistance is inferior.

In the present invention, the amount of the modified polyolefin resin present in the mixed resin in a particle state having a particle diameter of 0.1 to 5 μm is preferably in the range of 3 to 25 vol.% In terms of the volume fraction in the mixed resin. When the volume fraction is less than 3 vol.%, The impact resistance is not sufficiently improved, and when it exceeds 25 vol.%, The performance such as workability is deteriorated. Further, the number of modified polyolefin resins present in a particle state having a particle diameter of 0.1 to 5 μm per 1000 μm ³ of volume in the mixed resin is preferably in the range of ⁵ to 10 ⁵ . More preferably ^four 50 to 10. If it is less than 5, the impact resistance is not sufficiently improved, and if it exceeds 10 ⁵ , performance such as workability deteriorates.

  The thickness of the film of the present invention is preferably 5 to 50 μm. More preferably, it is 10 to 30 μm. When the thickness exceeds 5 μm, the impact resistance and workability are excellent. However, when the thickness exceeds 50 μm, the cost increases, and the effect of improving the impact resistance and workability is saturated. The thickness of the resin layer A is also preferably 5 to 50 μm.

  Below, the manufacturing method of modified polyolefin resin is described. Functional groups derived from carboxylic acids include carboxylic acid groups, carboxylic ester groups, metal salts of carboxylic acid ions, etc., and monomers containing these functional groups are copolymerized, graft polymerized, or blocked in polyolefin resins. By polymerization, a carboxylic acid-modified polyolefin resin is obtained.

  Specific examples of the monomer containing a functional group derived from carboxylic acid include 3 carbon atoms such as acrylic acid, methacrylic acid, vinyl acetate, vinyl propionate, maleic acid, maleic anhydride, itaconic acid, and maleic acid monomethyl ester. -8 unsaturated carboxylic acids, and metal salts in which all or part of these acids are neutralized with a monovalent or divalent metal cation such as sodium, potassium, lithium, zinc, magnesium, calcium and the like. The degree of neutralization is preferably 20 to 80%, more preferably 30 to 70%. However, the composition formed from the modified polyolefin resin having such a degree of neutralization is excellent in melt extrudability.

  Carboxylic acid esters include methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, n-propyl acrylate, n-propyl methacrylate, isobutyl acrylate, isobutyl methacrylate, n-butyl acrylate, methacrylic acid Examples include n-butyl, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, monomethyl maleate, glycidyl acrylate, glycidyl methacrylate, vinyl acetate, acrylic amine, acrylamide, and the like.

  These carboxylic acid-derived functional group-containing monomers are copolymerized or blocked with carboxylic acid-derived functional group-free olefin monomers such as ethylene, propylene, 1-butene, 1-pentene, isobutene, isobutylene, butadiene, styrene, acrylonitrile, etc. Carboxylic acid-derived functional group-containing modified polyolefin resin can be obtained by polymerization or graft polymerization. Among these, those in which a carboxylic acid group is graft-polymerized or copolymerized in a polyolefin resin exhibit high performance. A commercially available resin can also be used as such a modified polyolefin resin. For example, Modiper A (Nippon Yushi Co., Ltd.), Nukurel (Mitsui DuPont Polychemical Co., Ltd.), Bondine (Sumitomo Chemical Co., Ltd.), Admer (Mitsui Chemicals Co., Ltd.), And Tuftec (manufactured by Asahi Kasei Corporation).

  Further, those obtained by partially neutralizing these carboxylic acids with metal salts can also be used. With such a resin, the workability is slightly lowered, but higher impact resistance can be obtained. Examples of commercially available resins include Hi Milan (Mitsui DuPont Polychemical Co., Ltd.). Furthermore, when zinc oxide or calcium hydroxide is added when the carboxylic acid-modified polyolefin resin is melt-dispersed in the polyester resin, the carboxyl groups in the modified polyolefin resin are neutralized with those metal ions, and the carboxylic acid is partially metal A structure in which a carboxylic acid-modified polyolefin resin neutralized with a salt is dispersed in a polyester resin is obtained.

  A resin as a raw material is obtained by dispersing the modified polyolefin resin in a polyester resin. Examples of the dispersion method include, for example, melting and mixing two resins, maintaining the temperature to become one phase, then cooling to a temperature at which the two phases are separated, and using the phase separation to modify the modified polyolefin in the polyester resin phase A method in which the resin phase is dispersed, a method in which the two resins are dissolved in a common solvent and then the solvent is evaporated, and a modified polyolefin resin whose primary particle size has been reduced to 1 μm or less in advance at a temperature that does not aggregate in the polyester resin. A method of melting and dispersing, producing a polyester resin by polymerizing a monomer in a solution containing a modified polyolefin resin whose primary particle size has been refined to 1 μm or less in advance and a polyester resin constituent monomer, and the modified polyolefin resin is dispersed in the polyester In the modified state, and then melt-mixing the two resins and mechanically shearing the modified polyolefin resin A method in which thinning and the like.

  As an apparatus for mixing and melting, a mixing apparatus such as a tumbler blender, a Henschel mixer, or a V-shaped blender, or a melt mixing apparatus such as a single or twin screw extruder, a kneader, or a Banbury mixer can be used. At that time, temperature control of the mixing device and temperature control such as temperature change are made stricter than normal mixing methods, mixing time is made 3 to 10 times longer than normal mixing time, etc. Thermoplastic polyester resin by increasing the typical shear rate, for example, about 2 to 5 times faster than the normal rate, or combining them, for example, mechanically mixing with a tumbler blender and then melt mixing with an extruder A mixed resin in which a granular modified polyolefin resin having a particle diameter of 0.1 to 5 μm is dispersed is obtained. By processing a highly dispersible mixed resin obtained by melt-mixing with an extruder into a film, a resin film excellent in performance such as impact resistance in which the particle diameter of the modified polyolefin resin is more uniform can be obtained. Dispersing the modified polyolefin resin while processing into a film by melting a mixed resin with such a uniform particle size and high dispersibility in an extruder and processing it into a film, far out of the particle size distribution of the granular resin As a result, a film excellent in various performances can be obtained.

  Examples of inorganic particles that are effective in improving slipperiness, moldability, impact resistance, etc. include silica produced by dry and wet methods, porous silica, colloidal silica, titanium oxide, zirconium oxide, aluminum oxide, Examples thereof include calcium carbonate, talc, calcium sulfate, barium sulfate, spinel, iron oxide, and calcium phosphate. Organic particles or organic polymer particles include vinyl resins such as polystyrene particles, crosslinked polystyrene particles, styrene-acrylic crosslinked particles, acrylic crosslinked particles, styrene-methacrylic acid resin crosslinked particles, and methacrylic acid resin crosslinked particles. And organic polymer particles containing silicone, benzoguanamine-formaldehyde, polytetrafluoroethylene, polyphenyl ester, phenol resin and the like as constituent components. The content of these particles is not particularly limited, but in order to maximize performance, the particle size is preferably in the range of 0.01 to 5 μm. More preferably, it is in the range of 0.1 to 2.5 μm. Further, their particle size distribution is sharp, and the standard deviation is preferably 0.5 or less. Further, the shape of the particles is preferably close to a true sphere, and the ratio of major axis / minor axis is preferably 1.0 to 1.2.

In order to cope with severe molding, it is desirable that the mechanical properties of the resin film have a breaking elongation of 20% or more, preferably 50% or more, and a breaking strength of 20 N / mm ² or more. Here, the breaking elongation and breaking strength of the resin film were measured using a normal tensile testing machine, setting a 5 mm x 60 mm resin layer with a chuck distance of 30 mm, and pulling at a constant temperature of 25 ° C and a pulling speed of 20 mm / min. Can be done by testing. The tensile property at low temperature can be determined by conducting a similar tensile test at a constant temperature of 0 to 5 ° C. The resin sample for the test may be collected from any of a resin film, a laminated metal plate, or a processed container.

  Compared to ordinary polyester resins, these resin films have excellent adhesion to the base metal, high workability, excellent impact resistance, and sufficient flavor for normal use. It is suitable as a thermoplastic polyester resin film for laminating.

  Polyester resin having polyethylene terephthalate and / or isophthalic acid copolymerized polyethylene terephthalate as the main basic skeleton is a part of the polyester resin skeleton containing only ethylene glycol and terephthalic acid as a structural unit and / or ethylene glycol, terephthalic acid and isophthalic acid. The total of the parts having the structural units occupy 90% by mass or more, and the acid component may optionally copolymerize various aromatic dicarboxylic acids and aliphatic dicarboxylic acids at other sites.

  As described above, the upper mixed resin layer, that is, the resin layer A, is flexible and has excellent performance, but cracking and propagation in the resin layer due to thermal history and impact are remarkable, and performance such as corrosion resistance is poor. When sufficient, it is preferable to provide, for example, one or more layers of thermoplastic resin such as polyester resin in the lower layer (that is, on the metal plate side). Moreover, when high adhesiveness is required, it is preferable to provide the modified olefin resin containing carboxylic acid in the lower layer which touches a metal plate.

  In this case, the total thickness of the multilayer resin film including the mixed resin layer (upper layer) and the thermoplastic resin layer (lower layer) is preferably in the range of 5 to 50 μm. More preferably, it is 10 to 30 μm. When the thickness exceeds 5 μm, the impact resistance and workability are excellent. However, when the thickness exceeds 50 μm, the cost of the resin film increases, and the effect of improving the impact resistance and workability is saturated.

  Furthermore, when the thickness ratio of the lower resin layer to the upper resin layer (lower layer) / (upper layer) = 1/2 to 1/15, mechanical properties such as workability and impact resistance can be remarkably improved. It is more preferable to set the thickness ratio to 1/5 to 1/10. If the upper layer is thicker than this, the mechanical properties are very inferior. If the lower layer is thinner than this, a uniform thickness ratio cannot be obtained in the longitudinal direction and width direction during production, resulting in variations in performance.

  For example, when a polyester resin is provided in the lower layer, the glass transition temperature (Tg) of the polyester resin is preferably 30 to 100 ° C. More preferably, it is 50-80 degreeC. When the glass transition temperature is less than 30 ° C, the heat resistance of the polyester resin is inferior and scratches and the like are likely to occur due to the temperature rise during processing, and when it exceeds 100 ° C, the processability is inferior. The low temperature crystallization temperature (Tc) is usually 70 to 210 ° C, preferably 80 to 200 ° C, and the melting point (Tm) is usually 210 to 265 ° C, preferably 220 to 260. ° C. If the low-temperature crystallization temperature is less than 70 ° C., crystallization is likely to occur, so that the resin film is easily cracked or peeled off during retort treatment or the like, and if it exceeds 210 ° C., the mechanical strength of the polyester is inferior. If the melting point is less than 210 ° C, the resin deteriorates due to heat during processing, and cracks and pinholes are likely to occur.If it exceeds 265 ° C, crystallization proceeds by heat treatment such as drying and printing and baking during processing, Cracks and pinholes are likely to occur. The glass transition temperature, the low temperature crystallization temperature, and the crystal melting temperature are values measured by the methods described above.

  A resin film obtained by laminating an upper resin layer and a lower polyester resin layer mainly composed of polyethylene terephthalate and / or isophthalic acid copolymerized polyethylene terephthalate can be obtained by an ordinary multilayer resin extrusion method. That is, a mixed resin in which granular modified polyolefin resin having a particle diameter of 0.1 to 5 μm is dispersed in advance in the thermoplastic polyester resin of the present invention as a raw material resin for the upper layer in two different extruders using two extruders. And polyester resin with polyethylene terephthalate and / or isophthalic acid-copolymerized polyethylene terephthalate as the main skeleton as the raw material resin for the lower layer, respectively, melted and laminated from one T die by the feed block method or multi-manifold method Extruded in a state, cooled with a cooling roll, etc. to make a multilayer resin film and then laminated on a metal plate, or directly laminated by extruding a molten resin directly on a metal plate and sandwiching it with a cooling roll Laminated metal plates can be manufactured. As the T-die method, it is particularly preferable to manufacture by a multi-manifold method capable of controlling the melting temperature of a plurality of resins in detail.

  As a method for producing a laminated metal plate, a method of laminating by pressing a resin film on a metal plate heated in the range of the melting point of polyester resin to −70 ° C. to the melting point + 30 ° C. using a rotating roll is preferable. If the melting point of the polyester resin is less than -70 ° C., the adhesion to the metal plate is not sufficient, and if it exceeds the melting point of the polyester resin + 30 ° C., the resin film is fused to the laminate roll. Since the resin film of the present invention is excellent in processability and adhesion after heating, the optimum range of manufacturing conditions in the film laminate is wider than in the case of current resins, and labor saving and stabilization in manufacturing management and quality control are achieved. It becomes possible.

  As the resin film to be laminated, either a stretch-oriented resin film or a non-stretched resin film can be used. In particular, when a stretched resin film is used, as described above, the degree of orientation needs to be controlled to a target value by temperature control during thermal lamination.

  The resin film of the present invention makes it possible to produce a laminated metal plate by an extrusion laminating method, which is impossible with conventional polyester resins, because sufficient performance is obtained even when the resin film of the present invention is substantially non-oriented. Because it is.

  The primer layer may be provided as an adhesion layer with the metal plate as long as the effect of the present invention is not hindered. The laminated metal plate of the present invention is excellent in the primary adhesion between the resin layer and the metal plate, and the adhesion after processing, but in a severer corrosive environment or in an environment where better adhesion is required, A primer layer can be provided to give the required properties. For example, when used as a metal can, if the corrosive content is filled, the content enters the interface with the metal plate through the resin layer, corrodes the metal plate, and deteriorates the adhesion with the resin film. there is a possibility. In such a case, peeling of the resin layer can be prevented by providing an appropriate primer layer.

  The thermoplastic polyester resin film for laminating a metal plate of the present invention is suitable for an inner surface covering resin film of a two-piece metal can produced by drawing or ironing. Further, the resin film of the present invention is also suitable for a lid part of a two-piece can, or a trunk, a lid, and a bottom of a three-piece can. The laminated metal plate coated with the resin film of the present invention is excellent for workability, impact resistance, and adhesion, so it is suitable for thin-walled deep-drawn cans that are subject to severe processing due to a decrease in material thickness. is there.

  Further, in the laminated metal plate coated with the resin film of the present invention, since the resin film does not become cloudy during the retort processing, the can lid or the bottom of the resin film which is strongly required to prevent the cloudiness of the resin film, for example, a lid member of a two-piece can, It is suitable for a lid member and a can body member of a three-piece can.

  Next, the contents take-out property will be described in detail. In the resin film mainly composed of the polyester of the present invention described above, the interface free energy with respect to the water on the surface of the resin film that comes into contact with the contents when used as a container is 20 mN / m or less in order to improve the takeout of the contents. It is necessary to. Thereby, it is possible to obtain an excellent take-out property even for contents such as luncheon meat and spam. Although the detailed mechanism of this phenomenon is unknown, it is considered as follows. In other words, by controlling the surface free energy of water on the surface of the resin film to 20 mN / m or less, not only contents containing a lot of moisture such as luncheon meat, but also other contents (fish meat, vegetables, etc.) A thin film of water can be formed at the interface between the film and the contents. Since this thin film of water works to suppress adsorption of protein and cells derived from the contents, it prevents the contents from adhering to the resin film surface. The ability to form a water thin film is inversely correlated with the interface free energy with water on the surface of the resin film, and as the energy value decreases, the take-out property becomes better. In order to obtain better content take-out properties, the interface free energy with respect to water is preferably 10 mN / m or less, more preferably 5 mN / m or less. When the interface free energy is 1 mN / m or less, there is a concern that swelling on the surface of the material becomes severe and deformation becomes large.

  The interface free energy with respect to the water of the resin film surface prescribed | regulated by this invention must be maintained after the retort processing. The protein in the contents is heated by retort treatment and thermally denatured. Since the higher-order structure of the heat-denatured protein is destroyed, the steric configuration is changed by a hydrophilic group or a hydrophobic group present in the molecular chain in an undenatured state. Hydrophobic groups act to aggregate and precipitate by binding to each other hydrophobically (contacting the hydrophobic part with water is energetically disadvantageous, so proteins will aggregate and block the hydrophobic part from water) In other words, the denatured protein aggregates and precipitates.) The hydrophilic group is distributed in a large amount on the surface of the protein. For this reason, the protein after heat denaturation becomes easier to adhere to the resin film surface containing polyester as a main component. Therefore, the resin film surface containing polyester as a main component needs to maintain a thin film of water at the interface with the contents even after retorting. At this time, it is desirable that the resin film surface has a chemical composition that hardly dissolves in water. For example, when a hydrophilic resin layer such as cellulose is arranged on the resin film surface as it is, the interface free energy with respect to water on the resin film surface can ensure the range specified by the present invention, but the resin itself is water (from the contents). Since it melt | dissolves, there exists a possibility that it may transfer in the content and may impair flavor property, or the coating | coated property of a resin film may become inadequate, and corrosion resistance may deteriorate. Similarly, it is desirable that the hydrophilic group on the surface of the resin film is also fixed to the surface of the resin film and is not easily detached.

  On the other hand, even before the retort treatment, even if the interface free energy with respect to the water on the resin film surface is 20 mN / m or more, if the surface is modified during the retort treatment and the interface free energy is within the range of the present invention, excellent content Good take-out property is obtained. This is because if the interface free energy is adjusted to 20 mN / m or less before the protein is thermally denatured, a thin film of water is formed at the interface with the contents and functions as a protein adsorption suppression layer.

Next, as a method of setting the interface free energy with respect to water of the resin film containing polyester as a main component to 20 mN / m or less, -SO ₃ H, -SO ₃ M, -OSO ₃ M, -COOM It is preferable that hydrophilic groups such as, -COOH, -CO, -CN, -OH, and -NHCONH ₂ groups are present. Specific means for this purpose include 1) a technique for modifying the surface of a resin film by grafting treatment or coupling reaction treatment of a hydrophilic polymer or the like, and 2) a functional treatment such as hydroxyl group by a chemical treatment. Technology to introduce on the surface, 3) Technology to introduce functional groups such as hydroxyl groups to the surface of the resin film by plasma treatment or ultraviolet irradiation treatment, 4) Technology to add a surfactant or hydrophilic resin into the resin film, 5) Technology for coating the surface of a resin film with a hydrophilic polymer or the like.

  Examples of the hydrophilic polymer that can be used in the technique 1) include polyethylene oxide, polyacrylic acid, polyvinyl alcohol, polyethylene glycol, polyvinyl pyrrolidone, polyacrylamide, polyhydroxymethyl methacrylate, and cellulose derivatives (for example, carboxymethyl cellulose, hydroxyethyl cellulose, Methyl cellulose), amylose, alginic acid and the like, and copolymers and derivatives thereof. Further, hydrophilic in vivo substances such as albumin may be immobilized. It is particularly desirable to use polyethylene oxide.

  As a method of grafting treatment, vapor phase light irradiation grafting treatment, liquid phase simultaneous grafting treatment, and the like are suitable. Moreover, as a technique using a coupling reaction, the process which forms these layers by immersing in a silane coupling agent, a titanium coupling agent, and a silyl peroxide solution is mentioned. In particular, the use of a silane coupling agent is preferable, and the use of vinyltrichlorosilane and methacryloxypropyltrimethoxysilane can control the surface free energy with respect to the surface water to 20 mN / m or less.

  As the technique of 2), for example, a method of immersing in sodium hydroxide can be mentioned. Polar groups can be generated by hydrolysis reaction on the surface of the polyester resin. However, in order to make the free energy of the interface with water 20 mN / m or less, it is necessary to immerse for a long time, and the resin surface is likely to deteriorate, so care must be taken.

As the technique of 3), for example, glow discharge plasma (low temperature plasma) treatment which occurs under a low pressure gas having a relatively low electron density (10 ^{−2 to} 10 mmHg) can be mentioned. Since the energy of the active particles is high and the lifetime is long, it is possible to change only the surface and a surface layer with a depth of several thousand inches without damaging the properties of the polyester resin film. The interfacial free energy for water can be adjusted by changing the gas component of the atmosphere. Oxygen, nitrogen, and helium plasma treatment can control the free energy of the interface on the resin film surface to 20 mN / m or less. In particular, oxygen plasma treatment is suitable. For example, a technique of performing plasma treatment in a closed chamber filled with air or a peroxygen atmosphere energized by a radio frequency electromagnetic field can be used. Further, in the ultraviolet irradiation treatment, the interface free energy with respect to water can be controlled by optimizing the irradiation output. For example, by using a low-pressure mercury lamp with an output of 170 W (lamp current 0.6 A, voltage 280 V) as a light source and controlling the irradiation time, the free energy at the interface with water can be controlled to 20 mN / m or less.

  As a technique of 4), there is a method of adding a surfactant having a hydrophilic group and a hydrophobic group to a resin film. This diffuses to the surface and aligns the hydrophilic groups towards the air. As a result, the surface is hydrophilized and the interface free energy with respect to water can be controlled. The surfactant desirably includes at least one selected from an ionic surfactant, a nonionic surfactant, and an amphoteric surfactant. For example, ester compounds of aliphatic carboxylic acid compounds and aliphatic alcohol compounds, sucrose fatty acid esters, glycerin fatty acid esters, sorbitan fatty acid esters, propylene glycol fatty acid esters, and their ethylene oxide adducts, polyoxyethylene alkyls An ether system can be used. In particular, an aliphatic ester compound having a total carbon number of 10 to 120 constituting the surfactant is preferred from the viewpoint of compatibility of the polyester. Moreover, the process which adds a small amount of hydrophilic resin in a resin film is also suitable. A technique of adding polyvinyl alcohol (PVA), polyethylene glycol (PEG), or the like can be given, but since it is water-soluble, it is essential to use a technique for immobilizing it on the resin film surface.

  The technique 5) includes a method of coating a polymer having high hydrophilicity. The polymer having high hydrophilicity is not particularly limited as long as it is a polymer having a hydrophilic group such as a carboxyl group or a hydroxyl group. Polymethacrylic acid, (meth) methacrylic acid-alkyl methacrylate copolymer, polyhydroxyalkyl Methacrylate (eg, polyhydroxyethyl methacrylate), hydroxyalkyl methacrylate-alkyl methacrylate copolymer, polyoxyalkylene group-containing methacrylate polymer or a copolymer containing this, polyvinyl pyrrolidone, ethylene-vinyl alcohol copolymer, phospholipid / high Examples include molecular complexes. In particular, a technique for modifying a phospholipid copolymer on the surface of a resin is suitable. A technique of coating a phospholipid using a synthetic rubber is preferable.

  As the inorganic polymer, polysiloxane or the like is suitable. Forming a thin film consisting of siloxane bonds on the film surface, which hydrates with the water contained in the contents and generates silanol groups, making the surface hydrophilic and controlling the free energy of the interface to water below 20 mN / m Can do.

  Among the techniques 1) to 5), an optimum technique is selected in consideration of various properties required for the laminated metal plate for containers and industrial properties (productivity and economy). The technique of 4) is achieved, for example, by introducing a small amount of a specific additive into the polyester resin, so that there is little possibility of hindering productivity at a low cost, and the performance is almost the same as that of the polyester resin. Since it is easy to ensure an equivalent level, it is preferable.

  Furthermore, by adding a color pigment to the resin film containing polyester as a main component of the present invention, the underlying metal plate can be concealed and various color tones unique to the resin can be imparted. Further, it is possible to give a bright color using the metallic luster of the base without making the concealment perfect, and it is possible to give an excellent design. Unlike printing on the surface of the resin film, since the pigment is added directly into the resin and colored, there is no problem that the color tone is lost even in the container processing step, and a good appearance can be maintained.

  As the pigment to be added, inorganic pigments such as titanium dioxide and organic pigments can be used from the viewpoint of exhibiting excellent design properties after processing the container. Since these have strong coloring power and abundant malleability, they are suitable because good design properties are ensured even after processing the container. In particular, titanium dioxide is desirable for the resin film that comes in contact with the contents when used as a container according to the present invention. This is because after the container is opened, the color of the contents shines and a clean feeling can be imparted. These pigments are more preferable because they are rich in coloring power and spreadability and are safety and health substances approved by the FDA.

  When the resin film of the present invention has a multilayer structure of two or more layers, the pigment may be added to at least one of the layers.

  The amount of pigment to be added is not particularly defined, but in general, when it is contained at a mass ratio of 30% or more with respect to the resin film, the concealing property is saturated and economically disadvantageous. Here, the addition amount of the pigment is a ratio with respect to the resin layer to which the pigment is added (when added to the lower layer, the lower layer).

  Next, a method for producing a laminated metal plate by laminating the resin film of the present invention on a metal plate will be described. As described above, a manufacturing method in which the extruded resin is directly laminated on a metal plate can be applied. In the present invention, for example, a method can be used in which a metal plate is heated to a temperature exceeding the melting point of the film, and a resin film is brought into contact with both surfaces using a pressure-bonding roll (hereinafter referred to as a laminate roll) and heat-sealed. .

As the metal plate, an aluminum plate or a mild steel plate that is widely used as a material for cans can be used, and in particular, a surface-treated steel plate in which a two-layer coating made of metal chromium in the lower layer and chromium hydroxide in the upper layer is formed. (So-called TFS) is optimal. The amount of adhesion of the metal chromium layer and chromium hydroxide layer of TFS is not particularly limited, but from the viewpoint of adhesion and corrosion resistance after processing, in terms of Cr, the metal chromium layer is 70 to 200 mg / m ² , The chromium hydroxide layer is desirably 10 to 30 mg / m ² .

  In the method for producing a laminated metal plate according to the present invention, a resin is formed into a film, and in principle, the metal plate is coated so that the resin layer A is on the surface. If it is within the range, it is also possible to apply a melt extrusion lamination method in which the resin is melted without being formed into a resin film, and the surface of the metal plate is covered with the resin layer A.

Thickness 0.18 mm, degreased cold-rolled steel sheet width 977Mm, after pickling, CrO _3, F ^-, perform chromium plating with chromium plating bath containing SO ₄ ^2-, after intermediate rinsing, CrO _3, F ^- including A chromium-plated steel sheet (TFS) was produced by electrolysis with a chemical conversion solution. At this time, electrolysis conditions (current density, the quantity of electricity, etc.) adjusting the metal chromium coating weight and chromium hydroxide adhered amount of each of Cr terms was adjusted to ^{120mg / m 2, 15mg / m} 2. Next, using the metal strip laminating device shown in FIG. 1, the chrome-plated steel sheet 1 is heated with the metal strip heating device 2, and the laminate roll 3 is used as a container on one surface of the chrome-plated steel strip 1. Various resin films shown in Table 1 are laminated (heat-sealed) as the resin film 4a that comes into contact with the contents when it is used, and as the resin film 4b that comes to the outer surface of the container when used as a container on the other side. And laminated metal plates (Invention Examples 1 to 12, Comparative Examples 1 to 5) were produced.

  The resin films laminated in Invention Examples 1 to 12 have a single layer structure. In the resin films of Invention Examples 1 to 3, stearic acid monoglyceride is added as a surfactant, and the amount of addition is changed to adjust the interfacial free energy with respect to water. In the resin films of Invention Examples 4 to 6, oxygen gas is filled in the plasma VCM device, high frequency power is applied and low temperature plasma is irradiated, and hydrophilic groups are present on the film surface. The surface of the resin film of Invention Example 7 was subjected to ultraviolet treatment using a low-pressure mercury lamp with an output of 170 W (lamp current 0.6 A, voltage 280 V), and the interface free energy with respect to water was adjusted according to the irradiation time. In Invention Examples 8 to 9, the resin film surface is coated with polyvinylpyrrolidone which is a hydrophilic polymer. In Invention Example 10, the resin film surface is coated with polysiloxane by a sol-gel method from alkoxysilane, and a silanol group is generated by retort treatment to modify the resin film surface. In Invention Example 11, the terminal carboxylic acid of polyethylene glycol (PEG) is grafted to the hydroxyl group on the resin film surface by an ester bond. On the surface of the resin film of Invention Example 12, acrylic acid is grafted by the liquid phase light simultaneous grafting treatment.

  On the other hand, in Comparative Example 1, a polyvinyl alcohol resin film is formed on a polyester resin film. In Comparative Example 2, an ethylene / vinyl copolymer resin film (ethylene copolymer ratio 32 mol%) is formed on a polyester resin film. In Comparative Example 3, the polyester resin film surface is subjected to corona discharge treatment. In Comparative Examples 4 to 5, the polyester resin film has not been subjected to any treatment.

  The interface free energy with respect to water of the resin film coated on each of these laminated metal plates, contents removal property, and processability were investigated by the following methods.

(1) Interfacial free energy to water The contact angle when liquid is dropped on the surface of the laminated metal plate is θ, the dispersion force component of the interfacial free energy of the laminated metal plate is γs ^d , the polar force component is γs ^h , and the liquid interface When the free energy is γl, the dispersion force component is γl ^d , and the polar force component γl ^h , these satisfy the following relational expression.
γl × (1 + cosθ) / 2 × (γl ^h ) ^1/2
= (Γs ^d ) ^1/2 × (γl ^d ) ^1/2 / (γl ^h ) ^1/2 + (γs ^h ) ^1/2
Therefore, interfacial free energy known five liquid ^(γl, γl h, γl ^d is known) (water, glycerol, formamide, et thien glycol, dimethyl glycol) using a contact angle meter (Kyowa Interface Science Co., Using CA-D type), the static contact angle θ with respect to the resin film surface of water before and after retorting (130 ° C, 90 minutes) was determined (humidity: 55 to 65%, temperature 20 ° C), and the above are substituted into equation to determine the gamma] s ^d, gamma] s ^h and gamma] s the least squares method.

Next, assuming that the interfacial free energy of water is γw, γw ^h , and γw ^d , the interfacial free energy γ1w for water on the resin film surface can be obtained by the following relational expression.
γ1w = γs + γw−2 × (γs ^d × γw ^d ) −2 × (γs ^h × γw ^h )
(2) Content removal
(2-1) Evaluation of Ease of Ejection A disc having a blank diameter of 100 mm was punched out from a laminated metal plate, and a cup was produced by using a drawing machine at a drawing ratio (diameter before processing / diameter after processing): 1.88. Next, the salted meat for corned beef was filled in the cup, and the lid was wound up, followed by retorting (130 ° C., 90 minutes). Then, when the lid was removed and the contents were taken out with the cup upside down, the extent of the contents remaining inside the cup was observed, and the following evaluation was performed.
○: The contents can be taken out only by turning the cup upside down (without shaking by hand), and there is no deposit on the inner surface of the cup after taking out.
Δ: The contents remain inside the cup just by turning the cup upside down, but if the hand is shaken 2 or 3 times, there is no deposit on the inner surface of the cup.
×: It is difficult to take out the contents even if it is shaken a few times by hand.

(2-2) Observation of resin film surface after removal
The surface of the resin film after the contents were taken out in (2-1) was observed, the presence or absence of damage due to dissolution of the resin was observed visually and with an optical microscope, and the following evaluation was performed.
○: There is no dissolution of the resin and no surface damage is observed.
(Triangle | delta): Resin melt | dissolves a little and surface damage is recognized a little.
X: The resin is dissolved and surface damage is observed.

(3) Workability After applying wax on the laminated metal plate, a 179 mm diameter disc was punched out to produce a shallow drawn can with a drawing ratio of 1.80. Next, the drawn can was redrawn at a drawing ratio of 2.20, subjected to doming by a conventional method, trimmed, and subjected to neck-in-flange processing to produce a deep drawn can. The following evaluation was performed by paying attention to the neck-in part of the deep-drawn can thus obtained, visually observing the degree of damage of the resin film.
○: No damage was observed on the processed resin film.
(Triangle | delta): Although it can process, damage to a resin film is recognized partially.
X: The can is broken and cannot be processed.

  The results are shown in Table 1. The resin films coated on the laminated metal plates of Invention Examples 1 to 12 all have an interface free energy with respect to water of 20 mN / m or less, excellent content takeout properties, no film damage, and good workability. is there. On the other hand, all of the resin films of Comparative Examples 1 to 5 have an interface free energy with respect to water of more than 20 mN / m, and are inferior in any of the properties of content takeout and workability.

  Various resin films shown in Table 2 were laminated using the same TFS as in Example 1 in the same manner as in Example 1 to produce laminated metal plates (Invention Examples 1 to 13, Comparative Examples 1 to 4).

  The resin films laminated in Invention Examples 1 to 12 have a two-layer structure of polyester resin, and the modified polyolefin resin is contained only in the upper layer. In the resin films of Invention Examples 1 and 2, stearic acid monoglyceride is added as a surfactant, and the amount of addition is changed to adjust the interfacial free energy with respect to water. In the resin films of Invention Examples 3 to 4, oxygen gas is filled in the plasma VCM device, high-frequency power is applied and low-temperature plasma is irradiated, and hydrophilic groups are present on the film surface. The surfaces of the resin films of Invention Examples 5 to 6 were subjected to ultraviolet treatment using a low-pressure mercury lamp with an output of 170 W (lamp current 0.6 A, voltage 280 V), and the interface free energy with respect to water was adjusted according to the irradiation time. In Invention Examples 7 to 8, the resin film surface is coated with polyvinylpyrrolidone which is a hydrophilic polymer. In Invention Example 9, the resin film surface is coated with a polyoxyalkylene methacrylate polymer which is a hydrophilic polymer. In Invention Example 10, the resin film surface is coated with polysiloxane by a sol-gel method from alkoxysilane, and a silanol group is generated by retort treatment to modify the resin film surface. In Invention Examples 11 to 12, the terminal carboxylic acid of polyethylene glycol (PEG) is grafted to the hydroxyl group on the resin film surface by an ester bond. On the surface of the resin film of Invention Example 13, acrylic acid is grafted by the liquid phase light simultaneous grafting treatment.

  On the other hand, the resin films laminated in Comparative Examples 1 to 4 also have a two-layer structure of polyester resin, but in Comparative Example 1, an ethylene / vinyl copolymer resin film (ethylene copolymer ratio 32 mol%) is polyester. It is formed on a resin film. In Comparative Example 2, the polyester resin film surface is subjected to corona discharge treatment. In Comparative Examples 3 to 4, the polyester resin film has not undergone any treatment.

  The interfacial free energy with respect to water of the resin film coated on each of these laminated metal plates, contents take-out property, and processability were investigated by the same method as in Example 1.

  The results are shown in Table 2. The resin films coated on the laminated metal plates of Invention Examples 1 to 13 all have an interface free energy with respect to water of 20 mN / m or less, excellent content takeout properties, no film damage, and good workability. is there. On the other hand, all of the resin films of Comparative Examples 1 to 4 have an interface free energy with respect to water of more than 20 mN / m, and are inferior in any of the properties of content takeout and workability.

It is a schematic diagram of the laminating apparatus of a metal plate.

Explanation of symbols

1 Metal plate (TFS)
2 Metal belt heating device
3 Laminate roll
4a, 4b resin film

Claims (2)

A functional group derived from carboxylic acid is contained in a mass ratio of carboxylic acid in a mass ratio of 2 to 20 mass%, and a granular carboxylic acid-modified polyolefin resin having a particle diameter of 0.1 to 5 μm is contained in a mass ratio of 3 to 30 mass%. And a metal plate laminate having a resin layer (resin layer A) having an interface free energy with respect to water of 20 mN / m or less on at least one surface, the surface of the resin layer A being coated with a hydrophilic polymer. A laminated metal plate , wherein the thermoplastic polyester resin film is coated on at least one surface of the metal plate so that the resin layer A is the surface . 2. The laminated metal plate according to claim 1, wherein the thickness of the film is 5 to 50 μm .

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